Projectors including an illumination device including a solid-state light source that emits excitation light and a wavelength conversion element that is excited by the excitation light and emits fluorescence have been conventionally known (e.g., see PTL 1).
Specifically, a projector disclosed in PTL 1 includes an illumination device including an array light source, a collimator optical system, an afocal optical system, a first retardation film, a homogenizer optical system, a prism, alight emitting element (wavelength conversion element), a second retardation film, a diffuse reflection element, an integrator optical system, a polarization conversion element, and a superimposing optical system. In these components, the array light source, the collimator optical system, the afocal optical system, the first retardation film, the homogenizer optical system, the prism, the second retardation film, and the diffuse reflection element are located on a first optical axis, while the prism, the light emitting element (wavelength conversion element), the integrator optical system, the polarization conversion element, and the superimposing optical system are located on a second optical axis orthogonal to the first optical axis. The prism is disposed at a site where the first optical axis and the second optical axis intersect.
The array light source has a configuration in which a plurality of semiconductor lasers that are solid-state light sources are arranged in an array. Blue light of S-polarization that is laser light emitted from the array light source is converted to a parallel luminous flux by the collimator optical system, and adjusted in luminous flux diameter by the afocal optical system. The polarization axis of the blue light is rotated when the blue light passes through the first retardation film, which is a half-wave plate, and a portion of the blue light, which is S-polarized light, is converted to P-polarized light.
In an S-polarization component and a P-polarization component that are contained in the blue light, the S-polarization component is reflected by a polarization separation element of the prism, while the P-polarization component transmits through the polarization separation element.
The reflected S-polarization component is incident as excitation light on a phosphor layer of the light emitting element, and thus yellow fluorescent light is generated. The fluorescent light is unpolarized light whose polarization direction is not aligned. The fluorescent light transmits through the polarization separation element while remaining in the unpolarized state, and is incident on the integrator optical system.
On the other hand, the P-polarization component of the blue light transmitted through the polarization separation element passes through the second retardation film, and is diffusely reflected by the diffuse reflection element. This blue light is incident again on the second retardation film to thereby be converted to the S-polarization component, is reflected by the polarization separation element, and incident on the integrator optical system.
The integrator optical system includes a first lens array including a plurality of first lenses, and a second lens array including a plurality of second lenses corresponding to the plurality of first lenses. The integrator optical system divides illumination light containing the blue light and the fluorescent light into a plurality of partial luminous fluxes, and superimposes, together with the superimposing optical system, the plurality of partial luminous fluxes onto light modulating devices as regions to be illuminated. Between the integrator optical system and the superimposing optical system, the polarization conversion element is disposed, and thus the polarization direction is aligned.
Then, color lights (image lights) that are modulated by the light modulating devices are combined by the combining optical system, and thereafter enlarged and projected onto a screen by the projection optical device.